Ab initio study of phosphorus donors acting as quantum bits in silicon nanowires

Binghai Yan, Riccardo Rurali, A. Gali

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

A phosphorus (P) donor has been extensively studied in bulk Si to realize the concept of Kane quantum computers. In most cases the quantum bit was realized as an entanglement between the donor electron spin and the nonzero nuclei spin of the donor impurity mediated by the hyperfine coupling between them. The donor ionization energies and the spin-lattice relaxation time limited the temperatures to a few kelvin in these experiments. Here, we demonstrate by means of ab initio density functional theory calculations that quantum confinement in thin Si nanowires (SiNWs) results in (i) larger excitation energies of donor impurity and (ii) a sensitive manipulation of the hyperfine coupling by external electric field. We propose that these features may allow to realize the quantum bit (qubit) experiments at elevated temperatures with a strength of electric fields applicable in current field-effect transistor technology. We also show that the strength of quantum confinement and the presence of strain induced by the surface termination may significantly affect the ground and excited states of the donors in thin SiNWs, possibly allowing an optical read-out of the electron spin.

Original languageEnglish
Pages (from-to)3460-3465
Number of pages6
JournalNano Letters
Volume12
Issue number7
DOIs
Publication statusPublished - Jul 11 2012

Fingerprint

Quantum confinement
Silicon
electron spin
Phosphorus
Nanowires
phosphorus
nanowires
Electric fields
Impurities
Quantum computers
impurities
quantum computers
Spin-lattice relaxation
electric fields
Electrons
Ionization potential
Excitation energy
silicon
Field effect transistors
Excited states

Keywords

  • density-functional theory
  • electronic structure
  • excited states
  • hyperfine coupling
  • qubits
  • silicon nanowires

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Mechanical Engineering

Cite this

Ab initio study of phosphorus donors acting as quantum bits in silicon nanowires. / Yan, Binghai; Rurali, Riccardo; Gali, A.

In: Nano Letters, Vol. 12, No. 7, 11.07.2012, p. 3460-3465.

Research output: Contribution to journalArticle

Yan, Binghai ; Rurali, Riccardo ; Gali, A. / Ab initio study of phosphorus donors acting as quantum bits in silicon nanowires. In: Nano Letters. 2012 ; Vol. 12, No. 7. pp. 3460-3465.
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